This was an interesting piece of flash fiction. It had a great concept, though I don't know how Vikings could reverse engineer muskets and create enough gunpowder to storm England. I think it would have been better if you tossed in a point of view character, either from the Viking or the Welsh side, to show the action. This would give the reader someone to identify with, and make the impacts a little greater. Could have used some good metaphors and similes describing the boats and the battle too. Otherwise, nice job.